David Cameron says a deal struck with EU leaders will give the UK “special status” and he will campaign with his “heart and soul” to stay in the union.
The PM said the agreement, reached late on Friday after two days of talks in Brussels, would include a seven-year “emergency brake” on welfare payments.
He added it also included changes to EU treaties and would be presented to his cabinet at 10:00 GMT.
EU exit campaigners said the “hollow” deal offered only “very minor changes”.
The agreement on renegotiating the UK’s EU membership was announced by European Council president Donald Tusk, who tweeted: “Deal. Unanimous support for new settlement for #UKinEU.”
It paves the way for the UK to hold an in/out referendum on EU membership, which has been promised by the end of 2017 but is expected in June this year.
The new deal includes:
- Cuts in child benefit for the children of EU migrants living overseas – applicable immediately for new arrivals and from 2020 for the 34,000 existing claimants
- The amending of EU treaties to state explicitly that references to the requirement to seek ever-closer union “do not apply to the United Kingdom”, meaning Britain “can never be forced into political integration”
- An “emergency brake” on migrant workers’ in-work benefits that will apply for seven years – less than the 13 years the PM proposed but longer than other countries had asked for
- The ability for the UK to enact “an emergency safeguard” to protect the City of London, to stop UK firms being forced to relocate into Europe and to ensure British businesses do not face “discrimination” for being outside the Eurozone
German Chancellor Angela Merkel predicted the package of reforms would “elicit support in the UK for the country to remain in the EU”.
‘In Britons’ hands’
Mr Tusk said it “strengthens Britain’s special status”, while EU Commission president Jean-Claude Juncker described it as “fair”.
Mr Tusk added: “We didn’t walk away from the negotiating table. We were willing to sacrifice part of our interests for the common good, to show our unity.
“I deeply believe the UK needs Europe and Europe needs the UK. But the final decision is in the hands of the British people.”
Once Mr Cameron has briefed his ministers at Saturday’s cabinet meeting, they will be free to campaign for either side in the referendum.
Mr Cameron said he would shortly announce the date of the vote and said he was “disappointed” but not surprised that one of his key allies, Justice Secretary Michael Gove, was to campaign for the UK to leave the EU.
Analysis by Laura Kuenssberg, BBC political editor
The ink is hardly dry on the UK’s EU deal, but immediately the focus has switched to the substance of what David Cameron has achieved and – possibly an awkward question – how many of his colleagues will argue against him.
The focus will move to whether the prime minister can keep his party politely together during a period of public disagreement.
The ability to restrict benefits to migrants is an important victory for Mr Cameron – ammunition for his argument that he has achieved changes to help reduce the number of EU migrants coming to live and work in the UK.
The proposals are complicated and do not exactly match the promises he made in the Conservative Party manifesto.
But with it – and the other commitments – it becomes harder for his critics to make the case that the agreement is flimsy and will change nothing.
Mr Cameron said he had achieved the reforms he wanted, claiming they would put the UK “in the driving seat” of one of the world’s biggest markets and create a “more flexible” EU.
“We have permanently protected the pound and our right to keep it,” he added, saying that, for the first time, the EU “has explicitly acknowledged it has more than one currency”.
The prime minister said he had also protected Britain from further political integration inside the EU, adding: “Let me put this as simply as I can: Britain will never be part of a European superstate.”
‘Milk and honey’
Outlining his case to remain “in a reformed Europe”, Mr Cameron said “turning our back on the EU is no solution at all”.
“We should be suspicious of those who claim that leaving Europe is an automatic fast-track to a land of milk and honey,” he added.
“The British people must now decide whether to stay in this reformed European Union or to leave. This will be a once-in-a-generation moment to shape the destiny of our country.”
The deal reached between all 28 EU member states comes after several leaders objected to Mr Cameron’s planned reforms.
The original aim had been to conclude the deal at an “English breakfast” meeting on Friday, which became an “English brunch”, then an “English lunch” and eventually an “English dinner”, at which point the agreement was announced.
Eurosceptics have dismissed the reforms, saying they will not allow the UK to block unwanted EU laws or reduce migration.
Matthew Elliott, chief executive of the Vote Leave campaign, said Mr Cameron “will now declare victory but it is an entirely hollow one”.
He disputed the PM’s claim that the deal was legally binding, saying it “can be ripped up by EU politicians and unelected EU judges”.
LeaveEU co-chairman Richard Tice tweeted that the deal was a “desperate fudge”.
As the EU summit was being concluded, another EU exit campaign, Grassroots Out, held a rally in Westminster.
Conservative MP David Davis said it was time for Britain “to take control of its own destiny”, while UKIP leader Nigel Farage said the cross-party campaign was “absolutely united in fighting to get back our democracy”.
Mr Farage unveiled former Respect MP George Galloway as a “special guest” at the rally, describing him as a “towering figure on the left of British politics”.
Analysis by Laurence Peter, BBC News online
After two days of gruelling talks – and late-night haggling – EU leaders were plainly relieved to get the deal with David Cameron done.
French President Francois Hollande stressed that “no revision of the treaties is planned”. Tough EU treaty change would have been politically toxic for him, as he is faced with an election next year.
But he also stressed that for France the EU “is not just a budget” – but about many policies and “the joint project”. It was a pointed reminder about the EU’s symbolism, contrasting with Mr Cameron’s position.
German Chancellor Angela Merkel said the new child benefit rules could be good for Germany too – and supported Mr Cameron’s drive against abuse of the welfare system.
“I don’t think we gave the UK too much,” she said. But she admitted that ever closer union was an emotional issue for her, so Mr Cameron’s opposition to it was “not easy” to deal with.